Here's my script to control the Griffin Powermate. This enables you to get rid of the official (unsupported) Powermate software.
Per default, only left and right turn are assigned (mousewheel up and down), but you can easily add the other functions as well (button press, button press + turn left, button press + turn right.
Additionally you can also use modifiers (which is not possible with the official software). So you can use CTRL + Powermate turn left, etc...
And last but not least, you could also create different assignments, depending on which window has focus.

I'm indeed using the USB version of the Powermate. Unfortunately, I cannot say, if this will work with the bluetooth version.
However, you can try it first. Maybe it does work. And if not, there are ways to get this working

Hi, this script is so close to perfect for me, however my model of powermate shows up as a mouse (NOT a HID, so different usage page, identifying values such as no. of buttons instead of vendor ID, and will be outputting mouse-position-changes not keys)

Could you help me adjust your script to work with a mouse instead of HID? I've tried analyzing other mouse related scripts and hacking yours to match but alas, I am new to scripting and can't figure it out.